Regenerator and packing therefor



July 8, 1952 R. F. BENE NATI ETAL 2,602,645

REGENERATOR AND PACKING THEREFOR 3 Sheets-Sheet 1 Filed April 9, 1948 iler/arm if just/10m flTTOR/VE) y 8, 1952 R. F. BENENATI ETAL 2,602,645

I REGENERATOR AND PACKING THEREFOR Filed April 9, 1948 3 Sheets-Sheet 2 57 JNVENTORS fink/i Ffiemwah y Herman 75131004010 y 8, 1952 R. F. BENENATI ETAL ,6 5

REGENERATOR AND PACKING THEREFOR Filed April 9, 1948 3 Sheets-Sheet 5 V INVENTORS Faeri Z' ,fiznena it HTTORNEY Figure 6 is a horizontal section taken in a plane passing through line 66 of Figure 5 g thick and having integral interior fins l6 ex= tending from the inner wall in a radial direction toward the center of the tube to improve the efficiency of the heat exchange between the gaseous medium passing through tube l5 and that flowing over the packing members disposed on this supporting tube-. v Tube 1-5 may have an external diameter of from i/ 'to inches, preferably 3 inches. These packing members are formed by spot-brazing the leading end H of the strips woundon reel I4, as at l8, to the periphery of the tube I5, the several strips being disposed in, spaced relationship along the length Figure '7 is a plan view of. a modified form of regenerator packing member for use the portion of a regenerator through which no recycled gas is passed;

Figure 8 is a side elevational View showing the relative positions of the packing members of Figure 7 when disposed within the regenerator;

Figure 9 is a side elevational view of a modified form'of support for the strip or ribbon of high heat conducting material, which support may be used in forming the 'type of packing members shown in Figure '7; and

Figure 10 is a view of the base of the support of Figure9, looking up at the base.

In accordance with the process of this invention a regenerator packing is produced from a long strip or ribbon of high heat conducting material, such for example as aluminum or copper, preferably aluminum having one side 10 fiat'and theoppjosite'side ll provided with integral ribs or' projections [2. This strip has a brazing coating lla'of solder or any well known brazing material, e. g., aluminum-silicon composition in the case where the strip is of aluminum on at least one side thereof, desirably on the ribbed side II, the function of which coating will be explained hereinaftergf In order to provide the large mass of high heatconducting material and high area of cold exchanger surface per unit of regenerator volume necessary for effectively recovering the cold content of the outgoing products of rectification, it is important the material of high I heat conductivity of each of'the strips forming the packing members be relatively thin. 'Each strip may be from 1 to 6 inches wide, have ribs from .02 to .08 inch high, have a base thickness of from .01 to .04 inch and have the ribs spaced so that the distance from the center of one rib to the-center of the next rib is from .1 to .3 inch. Preferably each strip is dimensioned so that it is about 1 /4 inches wide, has a total thickness (the distance from the base of the strip to the top of the'integral rib or projection l2) of about .07 inch and a basethickness (the thickness of the base from which the ribs project) of approximately .02 inch, and has the ribs spaced so that the-distance from the center of one ribfto the center of the next rib is approximately15 inch.

- Inproducing the regenerator packing units of this invention, a plurality of such strips are wound on a support from a reel Hi, or a plurality of such reels, containing the desired number and lengths of strips.' The number of such strips applied to a support to form a packing unit will depend on the size of the regenerator in which the packing unit is to be disposed. A e

In the embodiment of the invention shown in Figure 1, the support comprises a tube It, de-' sirably a hollow tube of high heat conducting. material, forexample aluminum'or copper, having relatively thin walls, e. g., about .12 inch .oftube I5.- to formfa narrow space 19, preferably about inch :wide between adjacent packing members. As' shown in Figure 2, the leading end I! of each strip is planed or scarfed to provide a gradual taper conforming in general to the contour of the tubular support l5 resulting in the formation of a firm bond between the end of'this strip and the tubular support. 7 v

Thetubular support l5 containing the leading end of the strips spot-brazed thereto is then rotated to wind the strips thereon forming a multiplicity of convolutions of the strip material with the ribs of the first convolution 20. in con-- tact with the periphery of the tubular support l5 and the ribs 2i of the succeeding convolutions in contact with the fiat side of an underlying convolution. Tubular support I5 is. desirably coated on its outer surface with solder or brazing material as is the ribbed strip wound thereon. The terminal convolution 22 of the strip isplaned or scarfedso that it is generally reducedin thickness and terminates in a knife like edge 24. In this manner substantially cylindrical packing members result having anexternal diameter of from 3 to 1 2-inches, preterably 8 inches. ,While inthe showing of Figure 1 two strips are shownabout to be; wound in spaced relation on support I5, actually a larger number of, such strips are wound on support i5 .withnarrow spaces. l9;between adjacent .strips, the exact number-depending on thesize of the regenerator. Further, while in Figure 1 it is indicated the two strips, are wound simultaneously on support l5,.stripsapp1ied to thesuppor-t ,l 5 may be wound successively. :1 .The assembly ofthe tubular support l5 and packing members thereon, each consisting of a plurality of convolutions andproducedas here: inabove described. is then subjected to elevated temperatures and thereafter cooled tocause the libS.tOi.,bOI1d with the surfaces with which they contact. This bond is produced by the melting of the solder or brazing coating and subsequent solidification during 'cooling. In the case of packing members made from an aluminum strip and having an aluminum tubular support provided :with a brazing coating ofaluminum-silicon composition, the assembly produced as hereinabove described is desirably heated by stream of hotair to a temperaturev of .1000" F. and. then immersed-in a-molten salt bath at a temperature of 1150 F. -Under these'conditions the brazing coating-melts and upon removalof the assembly fromthe salt bath 'th'e molten brazing coating solidifies to produce-a firm bond between the ribs -and the flat surfaces of underlying-convolutions' and of the tubular-support where the ribs -c'on'tact same. The resulting assembly is then washed with hot= waterto remove molten salt" adhering thereto' and to insure that-the longitudinally extending channels 25 interrupted aeoa-e s Figure 5, section 29 may have disposed therein individual packing members, such as shown in Figure 7, assembled as shown in Figure 8. The packing member. of Figure 7 comprises a cyline drical tubular support on which is woundthe strip of high heat conducting material-having flat side I!) and ribs [2 to form longitudinally extending channels 25. The leading end of the strip is brazed to support 45 ancl the successive convolutions brazed to each other, as .hereinabove described in connection with-the construction of Figures 1 and 2., Top extension 46 and base extension 41 project from the opposite sides of the wound strip. Base extension 41 is provided with openings 48 leading into the central openinglflin support. I I I a The packing members of Figure '7 are assembled, as shown in Figure '8, with the base extension 41 of-a superimposed member resting on thetop extension 46 of an underlying memberforming agnarrow space 50 in between each pair of packingmembers: Any desired'numbenof such membersare assembled-in a. housing simply by piling successivemernbers ,within the housing with the base extension of, .each'resting on the top extension of anunderlying member. Ta I Inthe operation-of a regenerator section containing the packing members of Figures '7. and 8,

flow of the-gaseous media takesrplace through channels 25 and central opening 49;of each packing member. In the-spaces 50 between each pair of packing members flow takes place through openings 48 from the central openings 49 into the longitudinal. channels 25 and vice versa. Hence, turbulent flow takes place with optimum transfer of heat from the packing to the gas stream passing thereover during onecycle and from the gas to the packing during the next cycle.

In the modification of Figures 9 and 10, a tubular support has welded or otherwise secured to its base two strap members 52 and 53, each of a length slightly less than the diameter of the packing member. The strip'or ribbon or high heat conducting material of the type shown in Figure l is wound on support 5! with one edge resting on the strap members 52 and 53. The width of the strip or ribbon is such that the other edge is substantially 'in the same horizontal plane as thetop of support 51. .With the support of Figures 9 and .10 it i's not necessary to braze the strip or'ribbon to support, 5|, orf'the successive convolutions to each other since the weight of the strip. or ribbon is carried by, members 52 and 53 which also serve to space successive packing members when assembled to provide narrow spaces between successive pairs of' packing mem bers corresponding tospace's 50 (Figure 8). In other words, thefedge's' or; the convolutions rest on members 52 and '53 and are supportedthereby eliminating the necessity for .brazin'g successive convolutions to each, other tomaintain them in the desired fixed relationship. L

It will be noted the regenerator ofthisinvene tion has an exceptionally high Surface area or cold exchanger surface per unit of volume of regenerator. With the design of packing units hereinabove described involving packing members madefrom strips of aluminum;dimensionedias hereinabove described, the r egeneratormay have about 350 square 'feet of cold exchanger surface per cubic foot of regeneratorvolume. 'I he turbulent flow caused by the spacing-of the individ: ual packing members, as hereinabove described, further improves the cold transfer efficiency of the regenerator. Thezregenera'tor, is thereforerof exceptionally high transfer'efliciency. This makes it possible to have the volumetric space through which'the nitrogen. or, oxygen on the one hand and air ,on the other flow relatively small, there? by minimizing reversal losses. The feature of. the regenerator of this invention involving the positioning of each assembly .of supporting tube or rod and packing members in an individual housing permits ready testing .of the regenerator under actual operating conditions to determine whether the construction is gastight. Further,.should any leak develop in operation, it is a simple matter to determine which regenerator unit is faulty and to make the necessary repairto this unit.

The regenerators shown in Figures 4 and 5 are in a vertical position, the'airentering at the lower end and the product of rectification at the upper end. If desired, the regenerators may be inverted so that header alis above header 36; also the regenerators may be disposed in other positions than the vertical position shown.

A significant feature of this invention is the high radial thermal conductivity because of the multiple points of contact between the supporting tube and the first convolution of metal strip and betweenthe succeeding contiguous convolutions of metal strip. This radial-conductivity is of great importance in operating regenerators in oxygen plants where; the temperature difierence at the cold end (at a temperature of about 280 F.) between the rectification product stream entering during one period and the air leaving during the subsequent period of operation must be kept within the narrow range of about 5 to 10 F., preferably about 6 to 8 F. Such small temperature differences must be maintained in order that condensible impurities like carbon dioxide deposited in the regenerators by the air passing therethrough are completely removed-by evaporation during the passage of the rectification product stream through the regeneratorsand thereby the regenerators may be operated over long. periods without need of a plantshut-down to effect thawing of the regenerators.

It will be understood difierent embodiments of the .invention can be made without departing from the scope of this invention. For example, instead'of having-regenerator sections 28 anus in one housing, each section could be placed in an individual housing providing two regenerators instead of the unitary construction shown.

What is claimed is:

l. A regenerator comprising a hollow cylindric'al tube, a plurality of substantially cylindrical packing members on said tube arranged along the length of said tube with a narrow space between adjacent members, each member consisting of a plurality of convolutions of high heat conducting material, each of said convolutions having one side hat and the other side provided with closely spaced integral ribs extending across the width'of each convolution, the ribs of one convolution contacting and being bonded to the flat surface ofa contiguous convolution thereby forming in the annular. spaces between contiguous convolutions longitudinally extending channels' defined by said ribs, said channels being interrupted along their lengths by the narrow spaces between-adjacent members, a cylindrical housing enclosing the assembly of said packing members and said hollow tube but'having the opposite ends of said hollow tube projecting outside of said housing, said housing havinga diameter such that with said assembly disposed within said :housing little clearance is left between theouter periphery l of saidassembly-and the: inner: wallof said e'housing; and a port: in

the vicinity of each of; the opposite ends. or: said housing separatefrom'the flow of fluidthrough saidshollowtubep:

fluid ithereth rough; n a plurality: "of substantially cylindrical packing members on said tubearpranged along thelength thereof with a narrow jspacelb'etween" adjacent members, said packing members being bonded to; said hollow tube, each zpacking member consistingeta:plurality of connvolution's:of liigh heat conducting" materi'aheach *of\saidiitconvolutionsshaving one side flat and the otherlside provided 'withclosel-y: spaced 'in 'tegral ribs extending across the width of each convolution-"the ribs of one convolution contacting and being-bonded to th'e'fiat surface of a contiguous convolution thereby forming in the annular spaces between contiguous convolutions longitudinally "extending channels defined by said ribs, and the other section consisting of a support, a plurality of substantially cylindrical packing members on saidzsupport disposed along the length thereof with a narrow space between adjacent members, .a spacer member in said narrow spaceto maintain" the individual packing members in spaced relationship, each of said packing members consisting of a plurality of convolutions of high heat conducting material, ea ch of said convolutions having one side -flat and the-other side provided with closely spaced ribs extending across the' wi'dth of e'achc'ohvolutionthe' ribs of one convolution contacting and being bonded-'tdthe" flajt surfacefofa contiguous convolution thereby forming j in the annular spaces-between contiguous convolutions longitudinally extending channels defined by said ribs, a cylindrical housing enclosingboth sectionsf'but having the opposite ends-of said hollow tube projecting outside of said housing, said housing having a diameter such that with said sections disposed within said housing little clearance is left between the outer periphery of said sections and the inner wall of said housing, a port in the vicinity of each of the opposite ends of said housing to permit the flow of fluid through said housing separate from the flow of fluid through said hollow tube, and means at opposite ends of the assembly of packing members on said support for preventing movement of the individual packing members relative to said housing.

3. A regenerator comprising two sections, one

section consisting of a hollow tube for flow of a fluid therethr'ough, a plurality of substantially cylindrical packing members on said tube arranged along the length thereof 'with a narrow space between each pair of said members, said packing members being bonded to said hollow tube, each packing member consisting of a plurality of convolutions of a strip of aluminum, each of said convolutions having one side fiat and the other side provided with closely spaced integral ribs extending across the width of each convolution, the ribs of the first convolution contacting the tube and the ribs of each succeeding convolution contacting and being bonded to the fiat surface of a contiguous convolution thereby forming in the annular spaces between .the first convolution and the support and between the succeedingsconvolutions longitudinally extending channels defined by said ribs, said i'channelsk being :interrupted along their lengths "by the narrow, spaces between; adjacent members, ,thesecond 'section; comprising a rod-like support, a plurality of substantially cylindrical V packing members on said support disposed along the length thereof with 'anarrow space between adjacent-members, a spacer member inserted ineach of said narrow spaces to maintain the individual packing members in spaced relationship, each of said packing. members consisting of a plurality of convolutions of a strip of aluminum, each of said convolutions having ?one side flat and the; other side provided with closely spaced ribs" extending acrossthe width of'each convolution, theribsof the'first convolution contacting the support and the ribs of each succeedingv convolution contacting. and being bonded to the flat surface of a contiguous. convolution thereby. forming in the annular spaces between the first convolution and the support andbetween the. succeeding convolutions longitudinally extending channels defined bysaid cribs, said channels being interrupted along their lengths by the narrow spaces 'b'etween adjacent members-a cylindrical housing 'enclosing'fiboth sections but having the opposite ends of said hollow-tuber projecting outside of said housing, said housing having a diameter such that-with said sections disposed within said'housing little clearance-is left between the. outer periphery of said sections and the inner. wall of said housing,-a port in the vicinity of each of 'theopDQ- site ends of said housing to permit the. flow of fluid through; said housing separate" from the flow of fluid'through saidhollow tube, and means at opposite ends of the assembly of packing membersr -on1 said support "for preventing movement-of theindividual pa'cking members rela'* tive to said housing. P r s 4. A:regenerator assembly comprisingi'a pair of headers, a multiplicity of cylindrical housings disposed spaced relationship andcommuni cably' connecting said headers, each housing containing two sections, one section consisting of a tubularsupport, a plurality of substantially cylindrical packing members on said tubular support arranged along the length thereof with a narrow space between adjacent members, said packing members being bonded to said tubular support, each packing member consisting of a plurality of convolutions of high heat conducting material, each of said convolutions having one side fiat and the other side provided with closely spaced integral ribs extending across the width of each convolution, the ribs of one convolution contacting and being bonded to the flat surface of a contiguous convolution thereby forming in the annular spaces between contiguous convolutions longitudinally extending channels defined by said ribs, a second pair of headers outside of said cylindrical housings into which lead the upper and lower ends of said tubular support, the other section comprising a rod-like support, aplurality of substantially cylindrical packing members on said rod-like support disposed along the length thereof with a narrow space between adjacent members, a spacer member in said narrow space to maintain the individual packing members in spaced relationship, each of said packing members consisting of a plurality of convolutions of high heat conducting material, each of said convolutions having one side flat and the other side provided with closely spaced ribs extending across the width of each convolution, the ribs of one convolution contacting and being bonded -to the fiat Surface of a contiguous convolution thereby forming in'zthe annular'spaces'between contiguous c'onvoluti'ons' longitudinally extendingi channels definedby said ribs. 5

5; 'A iregenerator' assembly comprising a pair :of headers; a plurality of cylindrical housing disposed in spaced relationship and communicably connecting said headers; each housing containing twosections'; one section consisting -of a tubular support, a plurality of substantially cylindricalpacking members on said tubular support' arranged along the length'thereof with a narrow space between adjacent members, said packing members being bonded to said tubular support; each packing member comprising a plurality of.convolutions of astrip of aluminum, each of said convolutions having one side fiat and the other side provided with closely spaced integral ribs extending across the width of each convolution, the ribs of the first convolution contacting the tubular support and the ribs of each succeeding convolution contacting and being bonded to the flat side of a contiguous convolution forming in the annular space between the first convolution and the tubular support and the succeeding convolutions longitudinally extending channels defined by said ribs, said channels being interrupted along their lengths by the narrow spaces between adjacent members; a second pair of headers outside of said cylindrical housings-into which lead the oppo site ends of said tubular support; and the other section comprising a rod-like support, a plurality ofsubstantially cylindrical packing members on said rod-like support disposed along the length thereof with a narrow space between adjacent members, a spacer member inserted in each of said narrow spaces to maintain the individual packing members in spaced-relationship, each o'f'said packing members consisting of a plurality of convolutions ot a strip of aluminum,: each of said convolutions having one sideflat and the other side provided with closely spaced ribs extending across the width of each convolution, the ribsof the first convolution contacting the rod-like'support and the ribs of each succeeding convolution contacting and being bonded to the flat surface of a contiguous convolution forming in the spaces between the first convolutionand-the rod-like support and between the succeeding convolutions, longitudinally extending channels defined by said ribs, said wchannels being interrupted along their lengths by the narrow spaces'between adjacent members, and holding} means at :the. opposite ends of the assembly of cylindricalpacking members on said rod-like support'for preventing movement'of said packing membersrelative to saidhousing' in which said other section is disposed.

,6. A regenerator according to claim 1, wherein ,saidhigh heat conducting material "is aluminum.

, 1 ROBERT F. BENENATI. HERMAN F. BUSCHOW.

REFERENCES CITED The following references are of record in the file of this patent:

: UNITED STATES PATENTS Number I Great Britain June 1, 1938 

